kentucky_b,
Can you please check if the plugin you are trying to install is compatible with Eclipse 3.6 version?
If it is then you can add the plugin from the MyEclipse Configuration Center. Here are the steps:
1. Open MyEclipse , from menu options click on Help > MyEclipse Configuration Center. Choose software tab.
2. Click on *Add Site* this will open a window and Add from Archive. Select the zip file for the plugin.
3. This will list the software for the plugin, right click on the same and click on [Add to Profile]
4. Click on [Apply x changes] and follow the wizard
5. When prompted, please choose to restart the IDE
6. After installation, to verify that the plugin is added, click on Help > About MyEclipse > Installation Details > Plug-ins and look for the same.
Do let us know how it works for you.